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June 10-14 Severe/Flooding Wx - Obs, Radar, Warnings, Dmg. rpts


wxmeddler

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SquallOfDoom

 

a derecho out west doesn't necessarily mean much for us.. those guys get like 2 a year.

 

Though d2 from the SPC is stating the potential exists for a derecho event from northern IL through upper WV. That would be similar to last years set-up should it come to fruition */weenie*

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derecho is just a fun word for the media....

 

derecho should really only be used in a "nowcasting" framework -- it's pretty hard to predict whether a modeled MCS (even one modeled with a relative amount of certainty) will reach the necessary thresholds for classification as a derecho 

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Though d2 from the SPC is stating the potential exists for a derecho event from northern IL through upper WV. That would be similar to last years set-up should it come to fruition */weenie*

It could happen. I wouldn't say either way still. No reason people can't highlight the risk locally without mentioning the word. Then again it's just a word. But whatever happens tomorrow would want to come in late (and might be seperate) and run into a lower CAPE environment than last yr at least.. Even with that crazy environment ppl still thought the apps would finish it off. Both parts have sort of high ceilings but are also kind of conditional.
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SREF members says meh for tornado threat Thursday.

srefbks.JPG

SREF still pretty fast with the low. Guess the whole American suite is. Plus main risk prob near the warm front tho I think winds would end up more backed with a strong low to the north.
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derecho is just a fun word for the media....

derecho should really only be used in a "nowcasting" framework -- it's pretty hard to predict whether a modeled MCS (even one modeled with a relative amount of certainty) will reach the necessary thresholds for classification as a derecho

A year ago the media still thought a derecho was something on the menu at taco bell.

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yoda's going to be wrong about tomorrow. they might not slight us till tomorrow but it will happen.

 

I hate you

..MID ATLANTIC REGION    HAVE EXPANDED THE SLIGHT RISK EWD AS SWLY WINDS WILL LIKELY ADVECT  MID-UPPER 60S DEWPOINTS IN THIS REGION WITH DIABATIC HEATING  SUPPORTING MODERATE INSTABILITY. THIS AREA WILL EXIST ON SRN FRINGE  OF STRONGER MID LEVEL WINDS...AND STORMS MAY DEVELOP OVER THE HIGHER  TERRAIN AND SPREAD EWD INTO THE WARM SECTOR. OTHER STORMS THAT  DEVELOP OVER OH VALLEY MAY SURVIVE AS THEY CROSS THE MOUNTAINS.  PRIMARY THREATS WILL BE ISOLATED DAMAGING WIND AND LARGE HAIL.   
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The Interaction of Simulated Squall Lines with Idealized Mountain Ridges

Jeffrey Frame and Paul Markowski

ABSTRACT

Numerical simulations of squall lines traversing sinusoidal mountain ridges are performed using the Advanced Regional Prediction System cloud-resolving model. Precipitation and updraft strength are enhanced through orographic ascent as a squall line approaches a ridge. The simulated squall line then weakens as it descends the ridge because some of the cold pool is blocked by the terrain, resulting in less lift along the gust front and weaker convective cells. The flow within the cold pool accelerates slightly and the depth of the cold air decreases owing to upstream blocking, transitioning the flow in the cold pool head from subcritical to supercritical, then back to subcritical at the bottom of the ridge. A hydraulic jump forms when the flow transitions the second time, enabling the development of a new convective line downwind of the mountain. These new updrafts grow and eventually replace the older updrafts that weakened during descent. This process results in the discrete propagation of a squall line just downstream of a ridge, resulting in the formation of rain shadows downstream from topographic features. Discrete propagation only occurs if a ridge is of sufficient height, however. This replacement process repeats itself if a squall line encounters multiple ridges. The risk of damaging winds from a squall line is greater on the lee side of ridges and on the top of high ridges. These terrain-forced intensity fluctuations increase with mountain height, because the higher terrain permits even less cold air to flow over it. A wider ridge results in a more gradual orographic enhancement and downslope-induced weakening.

http://ams.allenpress.com/perlserv/?reques...175%2FMWR3157.1

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